The present invention relates to a valve arrangement for use with a valve system regulating delivery of a pressure medium, and more particularly, an arrangement for controlling operator-actuated delivery of a compressed medium to one or more consumers.
A known pressure medium regulating valve arrangement, in which a pedal serves as an operating element, is disclosed, for example, in the WABCO Westinghouse publication "Motorwagen-Bremsventil (motor car brake valve) 461 106 Page 1," August 1973 edition. In the arrangement described therein, a regulating spring in the form of an elastomer spring is located between a graduating piston and a ram. An outlet valve seat in this valve system is installed on the graduating piston and an inlet valve seat on the housing of the valve system. As a result, the pressure supplied by the valve system produces a force, hereinafter referred to as the "pressure force", which is exerted via the ram upon the operating element when the arrangement is actuated. In order to maintain actuation of the system, the operator must exert an actuating force in opposition to the pressure force (and negligible spring return forces), the magnitude of which depends on lever ratios between the operating element and the valve system, in addition to the pressure force. This means that for a given lever ratio, the actuating force is a function of the delivered pressure. The evolution of the actuating force as a function of the delivered pressure is referred to herein as the "actuating force requirement."
Often, an application requires a change in the above mentioned lever ratios, for example due to a change of the length of the operating element, while nevertheless requiring that a value of the actuation force requirement be maintained. Conversely, there are applications requiring a change in the actuation force requirement while the lever ratios remain unchanged. Such applications occur, in particular, when the installed actuating element is separated from the valve system, as is provided, for example, in the WABCO Westinghouse publication "Motorwagen-Bremsventil (Motor Car Brake Valve) 461 295," August 1973 edition. A comparable system is also disclosed in FIG. 4 on page 6 of the Clayton Dewandre Air Pressure Equipment Brochure "E, E-1, E-2, & DUAL E BRAKE VALVES." In such cases it, is not possible to properly adapt the system without changing the diameter of the graduating piston, and therefore not without requiring associated additional changes in the valve system. These changes, which require a redesign of the valve system, result in high development costs. Furthermore, the increased number of versions necessitated by such changes contribute to increased manufacturing, material and storage costs, among others drawbacks.
It is therefore the object of the present invention to develop an arrangement of the type mentioned above which permits the actuation force requirement thereof to be adapted to various applications with little or no changes in the valve system.